The research proposal carried out involved two projects which are based upon the ability of animals to produce barbiturate specific antibodies in response to immunization with a barbiturate-protein conjugate. In order to investigate whether immunized animals have an altered disposition or pharmacological response to subsequently administered barbiturates, the following procedures were accomplished: 1. A modified procedure for coupling the barbiturate to bovine gamma globulin was developed. This procedure produced an antigen capable of eliciting a higher titer of antibodies in both rabbits and mice. A colony of mice have been actively immunized against barbiturates and checked for antibody titer. Mice having specific antibodies circulating in their serum were tested for any altered disposition of phenobarbital. We have found that antibody producing animals do not handle barbiturates in the same manner as do a control colony of Freund's adjuvant treated animals. Specifically, in the immunized animals, serum levels of H3- phenobarbital were 2-3 times higher than in control animals. The effect that this altered disposition has on the brain levels of phenobarbital and the pharmacologic response to barbiturates is being investigated. 2. Antibodies obtained from immunized rabbits have been used to passively immunize mice. Initial experiments have demonstrated that antisera administered intravenously to mice retain their ability to bind barbiturates; the binding is due to a gamma globulin fraction and this gamma globulin fraction is active in binding ability at least up to 6 days following dosing. In these passively immunized mice the disposition of phenobarbital was altered, in that, significantly higher serum levels of the barbiturate were found at 1 hour following injection of H3-phenobarbital in mice passively immunized with barbiturate antiserum compared with control animals that received i.v. injection of normal rabbit serum. The effect that this altered disposition has on brain levels of phenobarbital and the pharmacologic response to barbiturates is to be investigated. The second project makes use of the ability of barbiturate antibodies to differentiate between parent drug (metharbital) and its metabolite (barbital). This has allowed the development of a very sensitive radioimmunoassay for barbiturate metabolism in vitro and in vivo. Using this method we are characterizing the ability of liver and non-hepatic tissue to metabli (Text Truncated - Exceeds Capacity)